When Google offered a series of concessions in order to settle its search-related antitrust investigation in Europe, some of those whose complaints had kicked off the whole affair were quick to dismiss Google’s proposals. And now it looks like the European Commission itself will also tell the U.S. firm to go back to the drawing board.

Google is accused of surreptitiously favoring its own services in its search results, locking advertisers onto its platform and scraping content from rival, subject-specific search engines. To settle the Commission’s investigation, it proposed labelling links to its own services, letting websites opt out of having their content show up in Google’s specialized search, and taking some of the lock-in out of its ad contracts.

On Tuesday, according to a Reuters report, EU Competition Commissioner Joaquin Almunia told European parliamentarians that it was a near-certainty that Google would have to revise its proposals. Referring to the extended period that Google’s rivals have been given to formally respond to the proposals, he said: “After, we will analyze the responses we have received, we will ask Google, probably, I cannot anticipate this formally, almost 100 percent we will ask Google: you should improve your proposals.”

When those proposals were formally revealed in March, Foundem – a British vertical search and comparison site that’s part of Microsoft’s anti-Google FairSearch organization – was quick to issue a comprehensive counter-argument (PDF warning). This more-or-less came down to Foundem saying Google’s proposals wouldn’t change the alleged inherent bias in its search rankings.

The European consumer protection organization BEUC also noted that the proposed concessions wouldn’t stop Google from manipulating its natural search results. In the U.S., by the way, the Federal Trade Commission (FTC) cleared Google of so-called “search bias”.

The European Commission had originally set a deadline of May 26 for responses to Google’s concessions. That has been pushed back to June 27. Apart from giving a pretty clear characterization of the responses the Commission has already received, Almunia said on Tuesday that he had not yet decided whether to press on with a formal antitrust investigation over Android — an investigation that was again called for by FairSearch.